Upcoming Talks

DK Discrete Mathematics

Speaker: ()
Date: Friday, 13.12.2019, 10:00-15:15
Room: Lecture room BE01, Styerergasse 30, ground floor

celebrating the beginning of the scientific
activities of the 3rd official funding phase
(01/2019 - 12/2022) of the doctoral program.

10:00 Opening

10:10 Talk by Prof. Klavdija Kutnar
(Rector, University of Primorska, Slovenia):
Lovasz's Hamiltonicity Problem

11:00 Musical interlude by Julian Zalla (e-piano)

11:15 Talk by Mahadi Ddamulira (DK-Project 09):
Repdigits as sums of three Padovan numbers

11:45-13:15 Lunch break

13:15 Talk by Irene Parada (DK-Project 11):
Extending drawings and arrangements

13:45 Musical interlude by Julian Zalla

14:00 Talk by Prof. Stephan Wagner
(Stellenbosch University & Uppsala University):
Coefficients of graph polynomials associated
with random trees and graphs

14:50 Musical finale by Julian Zalla

Mathematisches Kolloquium

Title: n points on the projective line
Speaker: Univ. Prof. Dr. Herwig Hauser (Universität Wien)
Date: 06.12.2019, 14:00 Uhr
Room: Seminarraum Analysis-Zahlentheorie, Kopernikusgasse 24, 2.OG

Deligne, Knudsen and Mumford developed the concept of stable curve in
order to find a geometric compactification of curves of genus g with n
marked points on them. They used quite a bit of heavy machinery to carry
out their constructions and proofs. In the talk, we will restrict to
genus zero, i.e., the projective line, and propose an elementary
approach, using graph theory and the concept of phylogenetic trees. The
lecture addresses a general audience.

Seminar für Kombinatorik und Optimierung

Title: Bilevel Knapsack Problems in a Stackelberg Model
Speaker: Ulrich Pferschy (Institut für Statistik und Operations Research, Universität Graz)
Date: 6.12.2019, 12:15
Room: Seminarraum AE06, Steyrergasse 30, Erdgeschoss

We consider a bilevel knapsack problem, in which one player, the follower,
decides on the optimal utilization of a bounded resource. The second player,
the leader, can offer incentives so that the follower chooses options
attractive also for the leader. Formally, each of the two players is
associated with a subset of the knapsack items. The follower selects a
subset of all items in order to maximize its overall profit. The leader
receives as pay-off only the values from those of its items that are
included by the follower in the overall knapsack solution. We consider the
case where the leader can offer part of the profit of every item to the
follower, and the case where the leader can set the weights of items for the
leader, aiming at a maximum weight of the selected leader's item.

In both cases the resulting setting is a Stackelberg strategic game. The
leader has to resolve the trade-off between offering highly attractive
incentives to the follower and thereby lowering its own pay-offs. We analyze
the problem for the case in which the follower solves the resulting knapsack
problem to optimality and obtain a number of negative complexity results.
Then we invoke a common assumption of the literature, namely that the
follower's computing power is bounded. Under this condition, we study
several natural Greedy-type heuristics applied by the follower.